1. Field of the Invention
The present invention relates to a phase adjusting device for performing phase (timing) adjustment of a pulse used for imaging in a digital camera, and a digital camera incorporating the phase adjusting device.
2. Description of the Related Art
In digital cameras (digital still camera, digital video camera, portable telephone with camera, and the like), an analog imaged signal that is imaged by an imaging element such as CCD and MOS image sensor is converted to a digital imaged signal, and such digital imaged signal is recorded after being subjected to a predetermined signal process. The pulse for driving the imaging element, the pulse for detecting the signal level, and the like are required to image the subject with the imaging element. Since the phase of such pulses has variations originating from manufacturing, it is difficult to adjust the pulse phase when designing hardware. Thus, the technicians perform phase adjustment after manufacturing, store information indicating the adjusted phase in a storage region, and thereafter, read out the phase information from the storage region in actual use to set the optimum phase.
A technique of mainly retrieving noise component with the exposure time at a minimum and adjusting the phase under the condition the high frequency component (noise component) becomes a minimum is conventionally known (see e.g., Japanese Laid-Open Patent Publication No. 2005-151081).
In the field of digital cameras, a system for incorporating the phase adjusting device is sometimes changed. In particular, in the field of medical cameras and the like, the imaging element is sometimes replaced after the digital camera is manufactured. If the incorporating system or the imaging element differs, the phase of the pulse for driving the same obviously differs, and thus the phase must be readjusted. However, it is difficult to rapidly and easily change the incorporating system and replace the imaging element if the technicians are manually readjusting the phase.
Although the pulse to be adjusted exists in a plurality of types, the respective optimum phase is obtained with the same method for all the pulses without taking into consideration the characteristics of each pulse in the Japanese Laid-Open Patent Publication mentioned above, and thus the accuracy is not very high.
Furthermore, in-vehicle camera etc. is also being widely used in recent years, and the optimum phase might greatly change due to temperature characteristics.